1. Field of the Invention
The present invention relates to an intake system for an internal combustion engine. Particularly, the present invention relates to an intake system for an internal combustion engine that takes in, cleans, and supplies the combustion air from outside to the internal combustion engine.
2. Description of the Related Art
A motorcycle has an intake system (intake system for an internal combustion engine) for supplying the combustion air to the engine (internal combustion engine). An air cleaner that cleans the air taken in from outside and supplies it to an engine combustion chamber is provided in the intake system for the engine (internal combustion engine) of the motorcycle. Additionally, some air cleaners provided in an intake system for a multi-cylinder engine have a function to distribute the air taken in from outside to each combustion chamber of the engine. For example, Patent Document 1 discloses a configuration in which a plurality of intake pipes are connected to an air cleaner. Additionally, according to the configuration of Patent Document 1, the combustion air can be distributed to each combustion chamber by the plurality of intake pipes.
Generally, a motorcycle has a valve apparatus that opens and closes between an intake port and a combustion chamber. A general valve apparatus has an intake valve driven by a cam, and opens and closes between the intake port and the combustion chamber by the intake valve. In some motorcycles, a solid cam is applied to the cam that drives the intake valve. The solid cam moves in an axial direction, and thereby can steplessly change a lift amount and lift timing of the intake valve. In this respect, in such a configuration, a drive source that moves the solid cam in the axial direction, and a cam position sensor that detects an axial position of the solid cam are disposed at a cylinder head cover, for example. In this case, it is necessary to avoid interference of an air cleaner disposed on an upper side of the cylinder head cover with a motor and a cam position sensor. As a configuration for avoiding the interference, for example, it is conceivable to dispose the air cleaner on a further upper side of the motor and the cam position sensor. However, such structure increases a size of an engine unit in a height direction. In addition, a configuration can be conceivable in which a cutout etc. are formed in the air cleaner so as not to interfere with the motor and the cam position sensor. However, such a cutout etc. formed in the air cleaner may cause a deviation in a flow of the air inside the air cleaner, and the air cannot be equally distributed to the combustion chamber. Furthermore, a capacity of the air cleaner may be reduced.
Patent Document 1
Japanese Laid-open Patent Publication No. 2004-84566